The plant size distribution differs systematically across developed and developing countries. For example, in developing countries, less than one fifth of 1% of plants are large (employ 100 or more employees) and account for about one fifth of total employment. In sharp contrast, in developed countries, more than 1.6% of plants are large and account for more than two fifth of total employment. In this dissertation, I develop a model of plant size to account for the differences in the plant size distribution observed in the data. In the first chapter, I explore the link between plant size distribution and economic development. I also discuss the main features of the plant size distribution data. The purpose of this data set is to provide evidence of systematic differences in plant size distribution across developed and developing countries. In the second chapter, I present a dynamic employment choice model in a life cycle setting. Then I calibrate the benchmark model to match some key features of the U.S. plant size distribution. I find that my model can capture the critical features of U.S. plant size distribution, including the upper tail which accounts for the bulk of the employment and output in the U.S. economy. In the third chapter, I explore how exogenous differences in aggregate barriers to investment and technology across countries affect the plant size distribution. Results indicate that exogenous differences in aggregate barriers to investment and technology across countries can account for more than 50% of the variation in both the fraction of large plants and employment share in large plants across countries. For the same group of countries, exogenous differences in aggregate barriers also account for 36% of the variation in the mean size.

This thesis centres around the issue of R&D, investment and growth: it is mainly concerned with the rationale which shapes the optimal investment pattern defined by a firm over time in a growing economy. We start considering the economy as a whole in order to evaluate how its actual functioning (interaction between research labs, risk of failure in innovating, patent laws and so on) shapes firms' specific investment policies. More precisely, we focus on the R&D process as it really develops in the market, and examine what is the optimal investment policy for firms involved in research and whether the selected investment policy in turn sustains the growth path of the economy. After analysing how the economic environment may affect firms' investment plans, we propose to identify the decision mechanism, as it develops inside the firm, through which an investment policy is defined over time. Thus, we move to an in-depth analysis of the process through which a profit-maximizing entity selects a specific investment policy when it is required to expand its production plant in order to satisfy a growing economy. / Cette thèse porte sur les questions de recherche et développements, d'investissement et de croissance : elle concerne principalement les raisons qui définissent au cours du temps l'investissement optimal dans une économie en croissance. Dans un premier temps, on considère l'économie dans sa globalité pour évaluer dans quelle mesure son fonctionnement actuel (interaction entre les laboratoires de recherches, risques d'échecs de innovations, licences, etc…) détermine les politiques d'investissement spécifiques des firmes. Plus précisément, l'analyse porte sur le processus de R&D qui se développe sur le marché et sur la politique d'investissement optimal pour des firmes impliquées dans la recherche. A son tour est analysée si la politique d'investissement sélectionnée soutient la croissance de l'économie. Dans un second temps, suite à l'analyse des effets de l'environnement économique sur les plans d investissement des firmes, nous proposons d'identifier le mécanisme décisionnel qui se développe a l'intérieur de la firme à partir duquel une politique d'investissement est définie dans le temps. Ainsi, nous présentons une analyse détaillée du processus à partir duquel une entité poursuivant la maximisation de son profit sélectionne une politique d'investissement particulière lorsqu'elle doit accroître sa production dans le but de satisfaire à l'économie en croissance.

Abstract In 2007, an adaptive grazing management process began on the Santa Rita Experimental Range (SRER) in southern Arizona with a primary management objective to reduce repeated defoliation of perennial bunchgrass plants during the summer growing season. In order to follow defoliation events, 1400 individual plants were identified in 6 pastures scheduled for summer grazing from June 15 to October 2, 2013. Plant height and diameter categories were measured before cattle entered each pasture and were re-measured daily or alternate days throughout the grazing period. The differences between heights and diameters were used to calculate any regrowth that occurred. Of the 1400 plants marked, 738 (52.7%) were not defoliated, 453 (32.3%) plants were defoliated once, 199 (14.2%) plants were defoliated twice, and 10 (0.7%) plants were defoliated three-times for a total of 881 defoliation events recorded. The majority of first defoliation events and first incidences of second defoliation occurred on day 3. Cattle began switching their grazing strategy from undefoliated plants to new growth of previously defoliated plants by day 9 with 48 of a total 161 previously defoliated plants being defoliated. The highest number of second defoliations were measured on day 11 when 115 plants were observed as having been defoliated for a second time and 5 plants were defoliated for a third time. Arizona cottontop (Digitaria californica) had a higher percentage of both single and multiple defoliation events when compared to the other perennial grass species. Distance from a permanent water source was not found to have a significant impact on the number of defoliations that an individual plant received. Plants defoliated the first time were taller and had a larger circumference (21.0±5.6 cm and 40.8±9.0 cm) than plants that were re-defoliated (15.5±5.6 cm and 31.4±9.0 cm). This study found that the planned 10 day SRER grazing rotation, when followed, would minimize multiple defoliations by cattle on perennial bunchgrasses.

The tundra is currently warming twice as rapidly as the rest of planet Earth, which is thought to be leading to widespread vegetation change. Understanding the drivers, patterns, and impacts of vegetation change will be critical to predicting the future state of tundra ecosystems and estimating potential feedbacks to the global climate system. In this thesis, I used plant traits - the characteristics of individuals and species - to investigate the fundamental structure of tundra plant communities and to link vegetation change to decomposition across the tundra biome. Plant traits are increasingly used to predict how communities will respond to environmental change. However, existing global trait relationships have largely been formulated using data from tropical and temperature environments. It is thus unknown whether these trait relationships extend to the cold extremes of the tundra biome. Furthermore, it is unclear whether approaches that simplify trait variation, such as the categorization of species into functional groups, capture variation across multiple traits. Using the Tundra Trait Team database - the largest tundra trait database ever compiled - I found that tundra plants revealed remarkable consistency in the range of resource acquisition traits, but not size traits, compared to global trait distributions, and that global trait relationships were maintained in the tundra biome. However, trait variation was largely expressed at the level of individual species, and thus the use of functional groups to describe trait variation may obscure important patterns and mechanisms of vegetation change. Secondly, plant traits are related to several key ecosystem functions, and thus offer an approach to predicting the impacts of vegetation change. Notably, understanding the links between vegetation change and decomposition is a critical research priority as high latitude ecosystems contain more than 50% of global soil carbon, and have historically formed a long-term carbon sink due to low decomposition rates and frozen soils. However, it is unclear to what extent vegetation change, and thus changes to the quality and quantity of litter inputs, drives decomposition compared to environmental controls. I used two common substrates (tea), buried at 248 sites, to quantify the relative importance of temperature, moisture and litter quality on litter decomposition across the tundra biome. I found strong linear relationships between decomposition, soil temperature and soil moisture, but found that litter quality had the greatest effect on decomposition, outweighing the effects of environment across the tundra biome. Finally, I investigated whether tundra plant communities are undergoing directional shifts in litter quality as a result of climate warming. Given the importance of litter quality for decomposition, a shift towards more or less decomposable plant litter could act as a feedback to climate change by altering decomposition rates and litter carbon storage. I combined a litter decomposition experiment with tundra plant trait data and three decades of biome-wide vegetation monitoring to quantify change in community decomposability over space, over time and with warming. I found that community decomposability increased with temperature and soil moisture over biogeographic gradients. However, I found no significant change in decomposability over time, primarily due to low species turnover, which drives the majority of trait differences among sites. Together, my thesis findings indicate that the incorporation of plant trait data into ecological analyses can improve our understanding of tundra vegetation change. Firstly, trait-based approaches capture variation in plant responses to environmental change, and enable prediction of vegetation change and ecosystem function at large scales and under future growing conditions. Secondly, my findings offer insight into the potential direction, rate and magnitude of vegetation change, indicating that despite rapid shifts in some traits, the majority of community-level trait change will be dependent upon the slower processes of migration and species turnover. Finally, my findings demonstrate that the impact of warming on both tundra vegetation change and ecosystem processes will be strongly mediated by soil moisture and trait differences among vegetation communities. Overall, my thesis demonstrates that the use of plant traits can improve climate change predictions for the tundra biome, and informs the fundamental rules that determine plant community structure and change at the global scale.

MATOS, Renata Fernandes de. Potencial genético de progênies de feijão-caupi para a obtenção de genótipos de porte ereto e ciclo precoce. 2016. 77 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, programa de Pós-Graduação em Agronomia / Fitotecnia, Fortaleza-CE, 2016 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-17T14:08:09Z No. of bitstreams: 1 2016_dis_rfmatos.pdf: 1230449 bytes, checksum: 768f7308433c8693df47c9706c1df439 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-17T14:08:23Z (GMT) No. of bitstreams: 1 2016_dis_rfmatos.pdf: 1230449 bytes, checksum: 768f7308433c8693df47c9706c1df439 (MD5) / Made available in DSpace on 2016-08-17T14:08:23Z (GMT). No. of bitstreams: 1 2016_dis_rfmatos.pdf: 1230449 bytes, checksum: 768f7308433c8693df47c9706c1df439 (MD5) Previous issue date: 2016 / In addition to high yield, the cowpea breeding programs have been based on the development of cultivars that erect associate and early cycle. This is because in addition to minimizing the risk of losses because the plants spend less time in the field, makes it easy to harvest, either manually or mechanically. For this purpose, are generally employed methods involving hybridization to give segregating populations, these, in turn, are driven by several generations of inbreeding. This process is costly and time consuming, and early identification of populations with potential for extraction lines, can greatly reduce the costs of a breeding program. For this, the methodology m + a, which estimates the concentration of favorable alleles in two consecutive generations, is a good indicator. Subsequently, it should identify the best genotypes within those potential people to compose the final testing lines, conditioning to obtain cultivars that meet the objectives of breeding programs. Thus, the aim of the first study (Chapter 1): (i) estimate the genotypic values (BLUPs) to agronomic important traits, and (ii) to investigate the potential use of the methodology m + a for the early selection of lines. In the second study (Chapter 2), aimed to verify the existence of genetic variability in the population and identify promising lines to compose the final rehearsals. To estimate the genetic potential of populations for early extraction lines were evaluated generations F3:4 and F3:5 ten progenies. These were evaluated in a randomized block design with three replications. To identify the best individuals to compose EFL, we used seeds from 119 genotypes originated ten progenies F3:4, and two witnesses, Sempre Verde and BRS Tumucumaque. It was used for this design in a 11 x 11 square lattice with two replications. The trials of the two studies were conducted in Marco-CE council and evaluated characters: number of days to flowering (NDF); number of days to maturity (NDM); plant height (ALT); pod length (CPV); number of seeds per pod (NGV); weight of 100 grains (M100G), and total mass (MTOT). We identified high heritability values in terms of average and accuracy for most of the characters, as well as low coefficients of variation, except for MTOT character. Positive and negative genotypic values of the progenies showed the potential to increase the expression of those characters related to productivity and reduce the expression of those associated with size and precocity. The estimate m + a more expressive for ALT was presented by the progeny obtained from the crossing of the EC-796 and MNC03-737E-5-10. And for NDF and NDM the progeny obtained from the crossing of the EC-796 and EC-954. The estimate the m + a was viable for identification of populations with potential for extraction lines in cowpea culture. In the second study, the genotypes 5, 7, 14, 15, 25, 27, 31, 42, 47, 57, 85 and 113 were those which showed greatest genetic potential for composing EFL. / Além de elevadas produtividades, os programas de melhoramento do feijão-caupi têm se baseado no desenvolvimento de cultivares que associem porte ereto e ciclo precoce. Isto porque além de minimizar os riscos de perdas, pelo fato das plantas passarem menos tempo em campo, facilita o processo de colheita, tanto manualmente como mecanicamente. Para tanto, geralmente são empregados métodos que envolvem hibridação para originar populações segregantes, estas, por sua vez, são conduzidas por várias gerações de endogamia. Esse processo é custoso e moroso e, identificar precocemente populações com potencial para extração de linhagens, pode reduzir consideravelmente os custos de um programa de melhoramento. Para isso, a metodologia m + a, que estima a concentração de alelos favoráveis em duas gerações consecutivas, é um bom indicador. A posteriori, cabe identificar os melhores genótipos dentro daquelas potenciais populações para compor os ensaios finais de linhagens, condicionando a obtenção de cultivares que atendam aos objetivos dos programas de melhoramento. Assim, objetivou-se no primeiro estudo (capítulo 1): (i) estimar os valores genotípicos (BLUPs) para caracteres de interesse agronômico, e (ii) verificar o potencial do uso da metodologia m + a para a seleção precoce de linhagens. No segundo estudo (capítulo 2), objetivou-se verificar a existência de variabilidade genética na população e identificar linhagens promissoras para compor os ensaios finais. Para estimação do potencial genético das populações para extração precoce de linhagens foram avaliadas as gerações F3:4 e F3:5 de dez progênies. Estas foram avaliadas no delineamento em blocos casualizados com três repetições. Para identificação dos melhores indivíduos para compor EFL, utilizaram-se sementes provenientes de 119 genótipos oriundos de dez progênies F3:4, e de duas testemunhas, Sempre Verde e BRS Tumucumaque. Utilizou-se para isso delineamento em látice quadrado 11 x 11 com duas repetições. Os ensaios dos dois estudos foram conduzidos no município de Marco-CE e avaliados os caracteres: número de dias para floração (NDF); número de dias para maturação (NDM); altura de planta (ALT); comprimento de vagem (CPV); número de grãos por vagem (NGV); massa de 100 grãos (M100G), e massa total (MTOT). Foram identificados elevados valores de herdabilidade a nível de média e acurácia para a maioria dos caracteres, assim como baixos coeficientes de variação, com exceção para o caráter MTOT. Valores genotípicos positivos e negativos evidenciaram o potencial das progênies para aumentar a expressão daqueles caracteres relacionados a produtividade e reduzir a expressão daqueles associados a porte e precocidade. A estimativa m + a mais expressiva para ALT foi apresentada pela progênie obtida do cruzamento entre CE-796 e MNC03-737E-5-10. E para NDF e NDM pela progênie obtida do cruzamento entre CE-796 e CE-954. A estimativa m + a foi viável para a identificação de populações com potencial para extração de linhagens na cultura do feijão-caupi. No segundo estudo, os genótipos 5, 7, 14, 15, 25, 27, 31, 42, 47, 57, 85 e 113 foram aqueles que demonstraram maior potencial genético para compor EFL.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / In addition to high yield, the cowpea breeding programs have been based on the development of cultivars that erect associate and early cycle. This is because in addition to minimizing the risk of losses because the plants spend less time in the field, makes it easy to harvest, either manually or mechanically. For this purpose, are generally employed methods involving hybridization to give segregating populations, these, in turn, are driven by several generations of inbreeding. This process is costly and time consuming, and early identification of populations with potential for extraction lines, can greatly reduce the costs of a breeding program. For this, the methodology m + a, which estimates the concentration of favorable alleles in two consecutive generations, is a good indicator. Subsequently, it should identify the best genotypes within those potential people to compose the final testing lines, conditioning to obtain cultivars that meet the objectives of breeding programs. Thus, the aim of the first study (Chapter 1): (i) estimate the genotypic values (BLUPs) to agronomic important traits, and (ii) to investigate the potential use of the methodology m + a for the early selection of lines. In the second study (Chapter 2), aimed to verify the existence of genetic variability in the population and identify promising lines to compose the final rehearsals. To estimate the genetic potential of populations for early extraction lines were evaluated generations F3:4 and F3:5 ten progenies. These were evaluated in a randomized block design with three replications. To identify the best individuals to compose EFL, we used seeds from 119 genotypes originated ten progenies F3:4, and two witnesses, Sempre Verde and BRS Tumucumaque. It was used for this design in a 11 x 11 square lattice with two replications. The trials of the two studies were conducted in Marco-CE council and evaluated characters: number of days to flowering (NDF); number of days to maturity (NDM); plant height (ALT); pod length (CPV); number of seeds per pod (NGV); weight of 100 grains (M100G), and total mass (MTOT). We identified high heritability values in terms of average and accuracy for most of the characters, as well as low coefficients of variation, except for MTOT character. Positive and negative genotypic values of the progenies showed the potential to increase the expression of those characters related to productivity and reduce the expression of those associated with size and precocity. The estimate m + a more expressive for ALT was presented by the progeny obtained from the crossing of the EC-796 and MNC03-737E-5-10. And for NDF and NDM the progeny obtained from the crossing of the EC-796 and EC-954. The estimate the m + a was viable for identification of populations with potential for extraction lines in cowpea culture. In the second study, the genotypes 5, 7, 14, 15, 25, 27, 31, 42, 47, 57, 85 and 113 were those which showed greatest genetic potential for composing EFL. / AlÃm de elevadas produtividades, os programas de melhoramento do feijÃo-caupi tÃm se baseado no desenvolvimento de cultivares que associem porte ereto e ciclo precoce. Isto porque alÃm de minimizar os riscos de perdas, pelo fato das plantas passarem menos tempo em campo, facilita o processo de colheita, tanto manualmente como mecanicamente. Para tanto, geralmente sÃo empregados mÃtodos que envolvem hibridaÃÃo para originar populaÃÃes segregantes, estas, por sua vez, sÃo conduzidas por vÃrias geraÃÃes de endogamia. Esse processo à custoso e moroso e, identificar precocemente populaÃÃes com potencial para extraÃÃo de linhagens, pode reduzir consideravelmente os custos de um programa de melhoramento. Para isso, a metodologia m + a, que estima a concentraÃÃo de alelos favorÃveis em duas geraÃÃes consecutivas, à um bom indicador. A posteriori, cabe identificar os melhores genÃtipos dentro daquelas potenciais populaÃÃes para compor os ensaios finais de linhagens, condicionando a obtenÃÃo de cultivares que atendam aos objetivos dos programas de melhoramento. Assim, objetivou-se no primeiro estudo (capÃtulo 1): (i) estimar os valores genotÃpicos (BLUPs) para caracteres de interesse agronÃmico, e (ii) verificar o potencial do uso da metodologia m + a para a seleÃÃo precoce de linhagens. No segundo estudo (capÃtulo 2), objetivou-se verificar a existÃncia de variabilidade genÃtica na populaÃÃo e identificar linhagens promissoras para compor os ensaios finais. Para estimaÃÃo do potencial genÃtico das populaÃÃes para extraÃÃo precoce de linhagens foram avaliadas as geraÃÃes F3:4 e F3:5 de dez progÃnies. Estas foram avaliadas no delineamento em blocos casualizados com trÃs repetiÃÃes. Para identificaÃÃo dos melhores indivÃduos para compor EFL, utilizaram-se sementes provenientes de 119 genÃtipos oriundos de dez progÃnies F3:4, e de duas testemunhas, Sempre Verde e BRS Tumucumaque. Utilizou-se para isso delineamento em lÃtice quadrado 11 x 11 com duas repetiÃÃes. Os ensaios dos dois estudos foram conduzidos no municÃpio de Marco-CE e avaliados os caracteres: nÃmero de dias para floraÃÃo (NDF); nÃmero de dias para maturaÃÃo (NDM); altura de planta (ALT); comprimento de vagem (CPV); nÃmero de grÃos por vagem (NGV); massa de 100 grÃos (M100G), e massa total (MTOT). Foram identificados elevados valores de herdabilidade a nÃvel de mÃdia e acurÃcia para a maioria dos caracteres, assim como baixos coeficientes de variaÃÃo, com exceÃÃo para o carÃter MTOT. Valores genotÃpicos positivos e negativos evidenciaram o potencial das progÃnies para aumentar a expressÃo daqueles caracteres relacionados a produtividade e reduzir a expressÃo daqueles associados a porte e precocidade. A estimativa m + a mais expressiva para ALT foi apresentada pela progÃnie obtida do cruzamento entre CE-796 e MNC03-737E-5-10. E para NDF e NDM pela progÃnie obtida do cruzamento entre CE-796 e CE-954. A estimativa m + a foi viÃvel para a identificaÃÃo de populaÃÃes com potencial para extraÃÃo de linhagens na cultura do feijÃo-caupi. No segundo estudo, os genÃtipos 5, 7, 14, 15, 25, 27, 31, 42, 47, 57, 85 e 113 foram aqueles que demonstraram maior potencial genÃtico para compor EFL.

No description available.

In this thesis, I combined field, common-garden and greenhouse experiments to examine the ecological and evolutionary consequences of plant-herbivore interactions in the perennial herb Lythrum salicaria. More specifically I examined (1) whether resistance and tolerance to damage from herbivores vary with latitude and are positively related to the intensity of herbivory in natural populations, (2) whether effects of herbivory on plant fitness vary with latitude, (3) whether populations are locally adapted and whether herbivory influences the relative fitness of populations, and (4) whether the intensity and effects of insect herbivory on reproductive output vary locally along a disturbance gradient and are associated with differences in plant resistance. A common-garden and a greenhouse experiment demonstrated that plant resistance decreased whereas plant tolerance increased with latitude of origin among populations sampled along a latitudinal gradient in Sweden. Oviposition and feeding preference in the greenhouse and leaf damage in the common-garden experiment were negatively related to natural damage in the source populations. Experimental removal of insect herbivores in three populations sampled along the latitudinal gradient demonstrated that intensity of herbivory and its effects on plant fitness decreased towards the north. A reciprocal transplant experiment among the same three populations showed that herbivory affected the relative fitness of the three populations, but did not detect any evidence of local adaptation. Instead the southernmost population had the highest relative fitness at all three sites. A herbivore-removal experiment conducted in nine populations in an archipelago in northern Sweden demonstrated that insect herbivory strongly influenced among-population variation in reproductive output. However, variation in resistance was not related to differences in intensity of herbivory at this spatial scale. Taken together, the results demonstrate that resistance and tolerance to herbivory vary with latitude but in opposite directions, that intensity of herbivory is a major determinant of flowering and seed output, and that the strength of herbivore-mediated selection varies among populations in Lythrum salicaria. They further indicate that both physical disturbance regime and latitudinal variation in abiotic conditions may strongly influence the performance and abundance of perennial herbs because of their effects on interactions with specialized herbivores.

Hydrogen can be produced from biomass; this hydrogen is called biohydrogen. Biohydrogen produced in Western Canada can partially contribute to meeting the demand for hydrogen needed for bitumen upgrading. Gasification and pyrolysis are two promising pathways for producing biohydrogen in a large-scale plant. Syngas, produced from the gasification of biomass, and bio-oil, produced from fast pyrolysis of biomass, can be steam reformed to produce biohydrogen. The cost of biohydrogen delivered by pipeline to a distance of 500 km is $2.20 per kg of H2, assuming that a plant utilizes 2000 dry tonnes of whole-tree biomass per day processing it in a Battelle Columbus Laboratory (BCL) gasifier. For forest residue- and straw-based biohydrogen plants the values are similar: $2.19 and $2.31 per kg of H2, respectively. Maximum economy of scale benefits are realized for biohydrogen production plants capable of processing 2000 and 3000 dry tonnes per day using BCL and GTI (Gas Technology Institute) gasification technology, respectively. The cost of biohydrogen from fast pyrolysis ($2.47 per kg of H2 from a 2000 dry tonne per day plant), using forest residue as the feedstock, is higher than the cost of biohydrogen produced by gasification. Carbon credits of about $120-$140 per tonne of CO2 are required to make biohydrogen competitive with natural-gas-based hydrogen.

Das Wissen über Mechanismen, die einen Einfluss auf Muster der Artenvielfalt und biotische Interaktionen haben, ist grundlegend für den Schutz von Biodiversität. Darüber hinaus kann es von direktem ökonomischem Nutzen sein, zum Beispiel im biologischen Pflanzenschutz oder bei Bestäubungsdienstleistungen. Die Größe eines Organismus kann ein solcher Faktor sein, der die Artenzahl und Interaktionen der assoziierten Organismen beeinflusst, denn große Organismen sind auffälliger als kleine und ihr Angebot an Ressourcen und Nischen für mit ihnen assoziierte Organismen ist oft reicher. Bezogen auf Pflanzen könnte daher die Größe einer Pflanze einen erheblichen Einfluss auf die Artenzahl der mit ihr assoziierten Arthropoden und ihre biotischen Interaktionen wie Herbivorie oder Bestäubung haben. Trotzdem ist der Einfluss der Pflanzengröße auf mutualistische und antagonistische Interaktionspartner der Pflanze und der sich daraus ergebende Einfluss auf die reproduktive Fitness der Pflanze bisher nicht umfassend und unter standardisierten Bedingungen untersucht worden. In der vorliegenden Studie wurden die Auswirkungen der Pflanzengröße auf die Artenzahl von Herbivoren, deren Gegenspielern und Bestäubern untersucht, sowie die Auswirkungen dieser Interaktionspartner auf die Pflanzenfitness. Dabei wurde zusätzlich zwischen endophagen und ektophagen Herbivoren und deren Gegenspielern unterschieden. Außerdem wurden die Herbivoren einzelner Pflanzenkompartimente und deren Gegenspieler separat analysiert. Des Weiteren wurde der Einfluss der Pflanzengröße auf den Herbivorieschaden an den verschiedenen Pflanzenkompartimenten und deren Einfluss auf die reproduktive Fitness der Pflanze, d.h. auf ihre Samenzahl, Tausendkorngewicht und Samengesamtgewicht, untersucht. Zuletzt wurde besonderes Augenmerk auf den Einfluss der Pflanzengröße auf mutualistische und antagonistische Blütenbesucher und deren Einfluss auf die reproduktive Fitness gelegt und untersucht, ob und inwiefern die reproduktive Fitness letztendlich von der Pflanzengröße abhängig ist. Zur Untersuchung dieser Fragen wurde ein „Common Garden“-Experiment angelegt. Um einen interspezifischen Pflanzengrößengradienten zu erzeugen, wurden 21 annuelle Pflanzenarten aus der Familie der Kreuzblütler (Brassicaceae) ausgewählt, deren Größe von 10 bis 130 cm reichte (gemessen als Pflanzenhöhe vom Boden bis zur Spitze). So konnten die Einflüsse des Habitats und der umgebenden Landschaft für alle Pflanzenarten standardisiert und trotzdem ein breiter Gradient realisiert werden. Dadurch hebt sich diese Studie von den bisherigen ab, die den Effekt von meist intraspezifischer Pflanzengröße auf die assoziierten Tiere anhand wild wachsender Pflanzen untersucht haben. Pflanzengröße sowie Zahl, Biomasse und Größe der unterschiedlichen überirdischen Pflanzenkompartimente (Blüten, Schoten, Blätter, Stängel) sowie Blütendeckung und -farbe wurden aufgenommen. Der Herbivorieschaden an diesen Pflanzenkompartimenten und die reproduktive Fitness (Samenzahl, Tausendkorngewicht und Gesamtsamengewicht) wurden gemessen. An und in Blüten, Schoten, Blättern und Stängeln wurden herbivore, räuberische, parasitäre und bestäubende Arthropoden gezählt. Die Pflanzengröße hatte einen positiven Einfluss auf die Artenzahl von Herbivoren, deren Gegenspielern und Bestäubern. Das traf ebenso auf endophage und ektophage sowie auf mit Blättern und Schoten assoziierte Herbivore und deren Gegenspieler zu. Des Weiteren konnte ein Anstieg des Herbivorieschadens an Blüten und Schoten mit zunehmender Pflanzengröße festgestellt werden, wohingegen der Schaden an Blättern und Stängeln von der Biomasse des entsprechenden Kompartiments positiv beeinflusst wurde. Der Schaden an Blüten hatte den stärksten Einfluss auf die reproduktive Fitness und reduzierte neben der Samenzahl auch das Tausendkorngewicht und das Gesamtsamengewicht der Pflanze. Die genaue Analyse der blütenbesuchenden Insekten ergab einen positiven Einfluss der Pflanzengröße auf die Abundanz und Artenzahl von Bestäubern (allerdings nicht bei extrem großem Blütenangebot), wie auch auf die Abundanz der adulten und juvenilen Rapsglanzkäfer und deren Parasitierungsrate. Steigende Rapsglanzkäferzahlen verringerten die Samenzahl sowie das Tausendkorngewicht, während die Bestäuber sich lediglich auf die Samenzahl positiv auswirkten. Insgesamt führte ein Anstieg der Pflanzenhöhe zu einer Abnahme des Tausendkorngewichts, aber nicht zu einer Veränderung der Samenzahl oder des Gesamtsamengewichts, was auf einen Ausgleich der Effekte von zunehmender Antagonistenzahl und zunehmender Mutualistenzahl hindeutet. Großen Pflanzen entstehen also durch ihre Auffälligkeit und Attraktivität für Herbivore hohe Fitnesskosten, wobei insbesondere der Blütenschaden durch Rapsglanzkäfer einen starken negativen Einfluss auf Samenzahl, Tausendkorngewicht und Gesamtsamengewicht hat. Diesen Fitnesskosten großer Pflanzen wirkt der Nutzen durch ihre Auffälligkeit und Attraktivität für Bestäuber entgegen, die die Samenzahl positiv beeinflussen. Hinsichtlich der Samenzahl sollten also große Pflanzen gegenüber kleineren im Vorteil sein, wenn die Insektengemeinschaft des Habitats von Bestäubern dominiert wird. Wird sie aber von herbivoren Blütenbesuchern dominiert, sollten kleine Pflanzen gegenüber großen einen Vorteil haben. Im Gegensatz dazu sollten große Pflanzen immer einen Nachteil bezüglich des Tausendkorngewichts haben, das von Antagonisten, nicht aber von Mutualisten beeinflusst wurde. Der Einfluss der Pflanzengröße auf biotische Interaktionen wurde bisher oft unterschätzt, obwohl er sich auf komplexe Weise über die mutualistischen und antagonistischen Insekten auf die reproduktive Fitness der Pflanze auswirkt.